As NPR's Larry Abramson reports, Panetta says the Pentagon is revising its cyber rules of engagement, so it can respond to those attacks.

LARRY ABRAMSON, BYLINE: In a speech to a business group in New York, Panetta said the threat posed by cyber attacks is no longer theoretical. The Shamoon virus disabled thousand of computers used by the energy industry in Saudi Arabia earlier this year. And Panetta said, computer attackers have already gained access to the systems that control America's chemical and water plants, and that control transportation systems.

SECRETARY LEON PANETTA: We also know that they are seeking to create advanced tools to attack these systems and cause panic, destruction, and even loss of life.

ABRAMSON: Panetta did not cite any damage caused by access to U.S. networks. The point of Panetta's speech was to explain that the Pentagon is working to respond to this threat. He did not explain whether the military envisions using offensive measures, such as the Stuxnet worm used against Iran's nuclear industry.

But Panetta did say the Pentagon is developing rules to determine when and how to respond to cyber attacks. Another point is to urge Congress to pass legislation requiring higher computer security standards for industry. Panetta said if Congress does not act, the president should issue an executive order.